Woodchucks (ground hogs), Marmota monax, are susceptible to viral hepatitis and thus are uniquely suitable for study of this disease and its apparent relationship to the development of hepatocellular carcinoma. However, usefulness of woodchucks in biomedical research is severely limited by the difficulty of breeding these animals in captivity and limited information about reproductive functions in this highly seasonal breeding species. The proposed studies are aimed at developing procedures for routine production of a large number of woodchucks under laboratory procedures for routine production of a large number of woodchucks under laboratory conditions. It will be determined whether woodchucks are spontaneous or induced ovulators by using daily measurements of hormone levels and serial laparoscopic examinations to monitor isolated and mated females. Protocols will be developed for induction of fertility during off season and effectiveness of these treatments will be further tested in animals that fail to breed in captivity at the normal time. Using video-monitoring and radio-telemetry, behavioral interactions of undisturbed woodchucks housed in the laboratory, in indoor/outdoor kennels and under semi-natural conditions in large outdoor enclosures will be characterized. Elements of behavioral interactions that relate to or predict success or failure of reproduction under laboratory conditions will be defined. In summary, we will correlate hormonal changes, reproductive behavior, and ovarian/testicular function with success or failure of conception. An immediate goal of the study is to increase natural conception (and recruitment) of woodchucks under laboratory conditions and to produce "off-season" litters by hormonal induction of fertility. The ultimate goal of these studies is to permit routine use of laboratory-bred woodchucks in biomedical research.